The "San Junipero" episode of "Black Mirror" has been hailed as brilliant and one of the few in the series with an optimistic vision of the future. (Again: major spoiler warning).

The series, now produced by Netflix, presents science-fiction short films about how tech could change the world in the near future.

"San Junipero" imagines a world where people can upload their brains into computers. Old people can live out fantasies in the virtual reality city of San Junipero. Dying people can be "uploaded to the cloud" and live there forever.

Futurist Robin Hanson, who wrote extensively about uploaded brains in "Age of Ems," saw the episode and wasn't impressed.

"As usual, it misses the huge implications to focus on minor ones," Hanson wrote in a message.

Hanson, an associate professor of economics at George Mason University who has a background in physics and computer science, predicts that we'll be able to upload brains within 100 years and that we'll have extensive virtual reality, so he thinks the show is believable there.

"The unrealism is in assuming the rest of the world stays the same, only effect is a new form of retirement," Hanson writes.

The rest of the world doesn't seem to have changed much in "San Junipero"— at least the parts that we see.

Hanson's prediction, by contrast, sees whole brain emulations (aka ems) radically and rapidly changing human society. Once brains can be uploaded to computers, he argues, we'll make countless copies of the most effective brains, running them at a thousand times human speed: soon ems will take over almost every job on the planet, while also building their own super-dense cities and evolving their own strange civilization. For more on Hanson's vision, read our interview with him.

While"San Junipero" doesn't reveal much about the broader world, there's not much evidence of radical social change. Retirement homes are populated by old people and staffed by young people, and it appears the only difference is having access to futuristic virtual reality.

Hanson, who has watched all of "Black Mirror," is dismissive of a lot of sci-fi.

"Even what they call hard science fiction tries often to get the physics or get the science right, but they're usually just laughably wrong about the social science," he told Business Insider.